improvement: pdf generation added to cases feature.

backend/prisma/migrations/20260718210000_lab_case_external_code/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "lab_cases" ADD COLUMN "externalCode" TEXT;

backend/prisma/schema.prisma

@@ -221,6 +221,8 @@ model LabCase {
   sentAt                    DateTime?
   dueDate                   DateTime?
   isImportant               Boolean   @default(false)
+  /// Optional code from an external lab app (e.g. exocad) for print/matching.
+  externalCode              String?
   accessToken               String?   @unique
 
   treatment       Treatment                @relation(fields: [treatmentId], references: [id], onDelete: Cascade)